Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0036341 (schizophrenia)
 60,220 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Two experiments with normal participants examined the effects of masking and masking task load on latent inhibition (LI, poorer learning for a previously exposed irrelevant stimulus than for a novel stimulus) as a function of level of schizotypality. In Experiment 1, a masking task was needed to produce LI. In Experiment 2, with low load, LI was present in low- but not high-schizotypal participants. In high load, LI was abolished in low-schizotypal participants, but only approached significance in high-schizotypal participants. The data support a distraction- rather than a resource-limitation model of attentional dysfunction in high-schizotypal normal participants. In addition, the data indicate that obtaining LI requires that some attention be initially allocated to the preexposed stimulus and then reduced. Implications of the model for understanding attentional dysfunction in schizophrenia are discussed.
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PMID:Are high-schizotypal normal participants distractible or limited in attentional resources? A study of latent inhibition as a function of masking task load and schizotypy level. 983 Feb 53

The electrically elicited blink reflex consists of three components (R1, R2, R3). In humans the excitability of these components is influenced by attentional states. In particular, distraction from the stimulus leads to facilitation of the bilateral R2 and R3. The present study was performed in order to investigate the excitability of the different components of the electrically evoked blink reflex in 13 patients with schizophrenia and 13 normal controls under standard conditions. Therefore, the thresholds of the distinct components were determined without any inhibitory or facilitatory procedure. There was no significant difference in R1 and R2 thresholds between patients and controls. In contrast, the R3 threshold was significantly reduced in schizophrenic patients (R3 threshold = 17.5 mA in normal subjects, 10.5 mA in patients, p = 0. 0001). In recent studies the R3 magnitude was found to be highly susceptible to changes in the attentional state of normal subjects. The lower threshold of R3 in patients with schizophrenia might therefore be a neurophysiological marker of attentional dysfunctions in schizophrenia.
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PMID:The electrically elicited startle blink reflex in patients with schizophrenia: A threshold study of different reflex components. 1007 63

Recent reports of spatial working memory deficits in schizophrenia provide evidence for dorsolateral prefrontal cortical (DLPFC) dysfunction. However, the question of how spatial working memory performance relates to other task impairments in schizophrenia considered reflective of frontal dysfunction, such as the Wisconsin Card Sorting Test (WCST) and smooth pursuit eye tracking, has been largely unexplored. Spatial working memory, as measured by a computerized visual-manual delayed response task (DRT), was evaluated in 42 schizophrenia patients and 54 normal controls. Subjects also completed a battery of neuropsychological and oculomotor tasks. Schizophrenia patients performed as accurately as controls on a no-delay, sensory-motor control condition, but showed a significant impairment in spatial accuracy with the addition of an 8-s delay and verbal distraction task. For the patients, working memory impairment was associated with fewer categories on the WCST, impaired eye tracking, fewer words learned on the Rey Auditory Verbal Learning Test, but not with measures of general cognitive and clinical functioning. Results suggest the presence of a sub-group of schizophrenia patients with common pathophysiology that accounts for the co-variance of several tasks implicating prefrontal dysfunction.
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PMID:Neuropsychological and oculomotor correlates of spatial working memory performance in schizophrenia patients and controls. 1042 9

The authors present a new rating scale for the psychotic symptoms of schizophrenia and related psychoses. The scale links specific symptoms of psychopathology to dysfunction and overactivity of dopaminergic mechanisms underlying the processes of reward and selective attention. The Rating Scale for Psychotic Symptoms (RSPS) is a 44-item rating instrument with a seven-point severity scale for each item. Psychotic symptoms are classified into three groups: Pathological amplification of mental images (perception symptoms) (subscale 1), Distraction symptoms (including catatonia and passivity experiences) (subscale 2), and Delusions (subscale 3). A dimensional, rather than a categorical, conceptualization of psychosis is assumed. Rating is accomplished through a manual and a semi-structured interview (SSCI-RSPS). In this first of two papers, general issues about the construction of the scale and the derivation of symptom groups are discussed. Dopamine-mediated modification of cortico-striatal synapses is seen as being of critical importance in all three groups of symptoms. In this first paper, we present subscale I (perception symptoms), which includes both amplified perceptual images (illusions) and hallucinations. A total of seven illusions and 11 hallucinations are rated as individual items.
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PMID:A rating scale for psychotic symptoms (RSPS) part I: theoretical principles and subscale 1: perception symptoms (illusions and hallucinations). 1046 58

This study tested the hypothesis that patients with a diagnosis of schizophrenia would report the use of different thought control strategies in comparison with non-patients. The Thought Control Questionnaire [TCQ; Wells, A. & Davies, M. (1994). The thought control questionnaire: a measure of individual differences in the control of unwanted thoughts. Behaviour Research and Therapy, 32, 871-878.] was administered to 22 patients who met DSM-IV criteria for schizophrenia and 22 non-patients. The results showed that schizophrenic patients used different thought control strategies (more worry and punishment-based strategies, less distraction-based strategies) in compairison with non-patients. The theoretical and clinical implications of these findings are discussed.
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PMID:Thought control strategies in schizophrenia: a comparison with non-patients. 1110 84

Two factors, 'anxiety-loaded' (AL) and 'perceptual-disorganization' (PD), emerged in a factor analysis of the Schizotypal Personality Questionnaire (SPQ). Sixty of the 219 participants performed a latent inhibition (LI) task. During the pre-exposure phase, one group was exposed to repeated non-reinforced presentations of an irrelevant stimulus and the other was not pre-exposed. In the subsequent test phase, learning was slower in the pre-exposed group than in the non-pre-exposed group. The LI effect was assessed, separately, as a function of SPQ, trait-anxiety sub-scale (TASS) of the State and Trait Anxiety Inventory (STAI), and AL and PD factors scores. LI was disrupted in participants with either high scores on SPQ, STAI, or the AL factor. A regression analysis indicated that both TASS and SPQ independently accounted for LI disruption in high schizotypals, but that the contribution of TASS was stronger. It was suggested that the anxiety component of schizotypy, more than the perceptual-disorganization (schizophrenia-like) component, accounts for the attentional dysfunction in high schizotypals, and for their greater than normal distraction by irrelevant stimuli.
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PMID:Is the attentional dysfunction in schizotypy related to anxiety? 1112 Apr 37

In order to examine the effects of risperidone on cognitive impairment in schizophrenia, event-related potentials (ERPs) were recorded before and after switching from conventional neuroleptics to risperidone in schizophrenic patients. ERPs were recorded during two auditory discrimination tasks (an oddball task and a distraction task) in 10 medicated schizophrenic patients during conventional neuroleptic and risperidone treatments. The amplitudes and latencies of N 100 and P300 component were measured in ERPs for target stimuli in the oddball task and in ERPs for target and novel stimuli in the distraction task. Although N 100 amplitude and latency and P 300 amplitude did not change significantly after switching the drug compared to that during conventional neuroleptic treatment, P 300 latency for target stimuli shortened significantly during risperidone treatment in both tasks, accompanied by the shortening of the reaction time in the distraction task. The P 300 latency change did not correlate with the change of the severity of psychopathology. These findings suggest that risperidone may speed the information processing in schizophrenic patients, contributing to the improvement of cognitive functions.
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PMID:Effects of risperidone on event-related potentials in schizophrenic patients. 1130 67

Cognitive deficits have come to be viewed as a hallmark feature of schizophrenic illness. Although laboratory based assessment of patients' cognitive deficits has been well investigated, few studies to date have examined the utility of clinical ratings of cognitive symptoms using the Schedule for the Assessment of Negative Symptoms (SANS) attention subscale. In this report, we examined the convergence between clinical ratings of cognitive impairment using the SANS attention subscale and performance on a variety of neurocognitive tests designed to measure attentional impairment, as well as other cognitive constructs such as working memory and executive functioning. A total of 56 acute schizophrenic inpatients were clinically rated with the SANS and completed the Continuous Performance Test, Digit Span Distraction Test, Wisconsin Card Sorting Task, and the Trailmaking Test. A series of correlational and regression analyses were conducted to test the concurrent and discriminant validity of the SANS attention subscale. Performance measures of attention, but not working memory or executive functioning, were significantly correlated with and moderately predicted the severity of SANS rated inattention. Additionally, the attention subscale was discriminated from the other SANS negative symptom subscales in predicting a laboratory measure of attentional functioning. The SANS attention subscale demonstrated both concurrent and discriminant validity. These data indicate that attentional dysfunction in schizophrenia can be meaningfully rated and interpreted using the SANS.
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PMID:Convergent validity and neuropsychological correlates of the schedule for the assessment of negative symptoms (SANS) attention subscale. 1158 9

This study was designed to examine whether discrete working memory deficits underlie positive, negative and disorganised symptoms of schizophrenia. Symptom dimension ratings were assigned to 52 outpatients with schizophrenia (ICD-10 criteria), using items drawn from the Positive and Negative Syndrome Scale (PANSS). Linear regression and correlational analyses were conducted to examine whether symptom dimension scores were related to performance on several tests of working memory function. Severity of negative symptoms correlated with reduced production of words during a verbal fluency task, impaired ability to hold letter and number sequences on-line and manipulate them simultaneously, reduced performance during a dual task, and compromised visuospatial working memory under distraction-free conditions. Severity of disorganisation symptoms correlated with impaired visuospatial working memory under conditions of distraction, failure of inhibition during a verbal fluency task, perseverative responding on a test of set-shifting ability, and impaired ability to judge the veracity of simple declarative statements. Severity of positive symptoms was uncorrelated with performance on any of the measures examined. The present study provides evidence that the positive, negative and disorganised symptom dimensions of the PANSS constitute independent clusters, associated with unique patterns of working memory impairment.
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PMID:Working memory correlates of three symptom clusters in schizophrenia. 1200 93

Spatial working memory deficits associated with dorsolateral prefrontal dysfunction have been found in Caucasian samples of schizophrenia patients and their first-degree relatives. This study evaluated spatial working memory function in affected and unaffected members of multiplex schizophrenia families from the Republic of Palau to determine whether the spatial working memory deficits associated with schizophrenia extend to this non-Caucasian population. Palau is an isolated island nation in Micronesia with an elevated prevalence of schizophrenia and an aggregation of cases in large multigenerational families. Our objective was to evaluate the potential for spatial working memory function to serve as one of multiple endophenotypes in a genetic linkage study of these Palauan schizophrenia families. A spatial delayed response task requiring resistance to distraction and a sensorimotor control task were used to assess spatial working memory in 32 schizophrenia patients, 28 of their healthy first-degree relatives, and 19 normal control subjects. Schizophrenia patients and their relatives were significantly less accurate than normal control subjects on the spatial delayed response task but not on the sensorimotor control task. On both tasks, patients and relatives were slower to respond than the normal controls. There were no age or gender effects on accuracy, and working memory performance in schizophrenia patients was not significantly correlated with medication dosage. In summary, spatial working memory deficits that have been found in Caucasian schizophrenia patients and relatives were confirmed in this isolated Pacific Island family sample. These results suggest that spatial working memory deficits may be a potentially useful addition to the endophenotypic characterization of family members to be used in a comprehensive genome wide linkage analysis of these Palauan families.
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PMID:Spatial working memory deficits in schizophrenia patients and their first degree relatives from Palau, Micronesia. 1221 Feb 74


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